Designed by MC2 Audio, the AD-9 utilises proprietary Class-D amplifier technology, combined with a dual feedback loop system to give excellent transient response. The resonant power supply has a very large power reservoir, which allows the AD-9 to deliver high transients without any perceptible “bass sag”. This, along with the aluminium chassis construction are the keys to the very low weight, which makes the AD-9 as ideal for touring applications as it is for fixed installations. The design of the AD-9 utilises a progressive switching rail output, which enables the high voltage swings required to produce peak power capability without compromising the sonic performance.

The AD-9 features newly designed limiters, which are linked to the output current monitors and power supply which keep mains input and output currents within safe operating limits at all times, whilst maintaining the transparent sonic performance required. The inbuilt Power Reduction Control is also tied into these limiters – as well as the power supply, and continually monitors these as well as load, temperature and other operating parameters. Activated via recessed switches on the rear panel, the PRC effectively reduces the available power output from the amplifier. This allows the user to set the AD-9 to have a maximum power below its rated output, ensuring the best possible match to a wide variety of different loudspeakers and improving overall system reliability.

The front panel for the AD-9 carries the AC mains power switch and indicator LED, as well as 5-segment LED meters, indicators for channel input link, PRC activation, bridged mode and audio protection. Each channel also has a multi-detent analogue level control allowing precise signal level settings when in use. Amplifier protection is also an area where the AD-9 delivers completely. A soft-start sequence with complete inrush protection means the AD-9 powers up completely muted, and then gradually fades the input up to the previous level. A comprehensive diagnostic circuit constantly monitors load, temperature and other parameters and automatically adjusts the power supply if overheating or any other problems occur. Output short circuit and DC output are also protected – and the AD-9 will only require a manual restart if output short circuits occur.

The AD-9 is built around a 2U all-metal chassis, which provides a roadworthy package whilst keeping the weight low. Handles are included within the front 5mm thick fascia panel. A rackmount kit is also supplied to enable the amplifier to be secured at the rear for additional stability. Low-noise variable speed fans are fitted to the AD-9 (cooling is from front to rear), along with a reticulated foam dust filter which can easily be removed for cleaning.

The rear panel houses the Neutrik XLR input connectors, along with output connectors on SpeakON NL4. The captive AC mains power cable is also presented on the rear panel, along with the recessed switches for bridged mode, input signal link and the PRC controls for each channel.